Carburetor accelerating pump with gas vent



F. A. KOMMER CARBURETOR ACCELERATING PUMP WITH GAS VENT Filed Jan. 24,1952 INVENTR.

FRED A. KOMMER F 10,4. W Z,

ATTORNEY CARBURETOR ACCELERATING PUMP WITH GAS VENT Fred A. Kommer, St.Louis, Mo., assignor, by mesne assignments, to ACE Industries,Incorporated, New York, N. Y., a corporation of New Jersey ApplicationJanuary 24, 1952, Serial No. 267,942

7 Claims. (Cl. 261-34) This invention relates to carburetors forinternal combustion engines and, more particularly, to improvements in anovel type of accelerating pump such as'is shown in aco-pendingapplication of John S. Carrey, Serial No. 117,772, filed September 26,1949, entitled Carburetor, now Patent No. 2,619,533 of November 25,

Inthe prior device, the accelerating pump was pro- ,lvided with aconstantly open inlet to the pump chamher. This Was for the purpose ofpermitting the fuel from thefuel bowl to fill the pumping chamber, and,

incidentally, to vent from the chamber any accumulation "of vapors orgases which might tend to produce a vapor'1ock in the accelerating pump.This arrangement was found not completely satisfactory for the 'latterlpurpose, since the static head of liquid pressure prevented the gasesfrom escaping. The present disclosure "relates to a modification of thepump which provides adequatetand suitable venting and prevents vaporlock.

The invention has been illustrated as applied to a diaphragm type ofpump, but it is obvious that the type of pump, whether piston ordiaphragm, is immaterial to v the functioning of the present invention.

In the above-mentioned application, a diaphragm .pump has beendisclosed-which is actuated by throttle movement, as well as by manifoldsuction. While this particular type of pump is'presently regarded asmore satisfactory in operation than one actuated exclusively by eitherof these means separately, the actuation is not f regarded as a part ofthe present invention, except insofar as the elimination of gases andvapors improves pump operation and fuel metering.

. One of the objects of the invention is to provide an improvedarrangement of accelerating pump for a carburetor, which incorporates avent from the highest point in the pumping chamber.

Another object of the invention is to provide a pump chamber with a ventconnected to atmosphere and a port exposed at the point of gasaccumulation in the pump chamber.

Another object of the invention is to provide a pump chamber vent andvalve to effectively regulate delivery of fuel from the pump. Anotherobject of the invention is to provide a pump delivery throttling meansfor controlling the rate of rein section.

'Fig. 2 is an enlarged sectional view of the pump shown in'Fig. 1, inmid-stroke. I I

United States Patent'O shoe washer 36.

-Fig. 3 is an enlarged sectional view of a modified form of pump. r

Fig. 4 is an enlarged sectional view of the pump shown in Fig. 3, inmid-stroke. I

Referring, first, to Fig. 1, the drawings show a car'- buretor,generally indicated as provided with a mixing tube or conduit 11,containing the usual venturi tubes and nozzles (not shown) centrallysupported in the conduit 11. A throttle shaft 12 supports a throttlevalve 13 at the lower end of the mixing conduit 11, and a flange 15 isprovided for attachment of the carburetor to the intake manifold of theengine. As shown in section, the source of fuel supply is a fuel line(not shown) and constant level fuel chamber 16 which includes a floatand a float controlled needle valve (not shown) for. maintaining fueltherein at a constant level.

Adjacent the bottom of the fuel bowl is a metering orifice element 17controlled by a. stepped metering pin 18 shown in its lower position inFig. 1. Passages 19 t and 2t) connect the metering orifice element witha main nozzle passage 21. t

Within the constant level fuel chamber is a depression or cavity 22forming a chamber which is closed at its upper side by a diaphragm 23secured in place by an inverted cup 24. Both cup and diaphragm cooperateto form a pumping chamber 25, which communicates with the constant levelfuel chamber 16 by means of anopening or conduit 26 in the upper portionof the cup 24.

An annular screen maybe provided in the upper surface of the cup, ifdesired, for the purpose of filtering impurities from the fuel beforeentry of the fuel into the pumping chamber through the opening 26. Aconduit .27 is provided opening into the inverted cup 24,'which isconnected with a nozzle 27a in the fuel mixture conduit 11. A continuouspassageis formed by conduit26, chamber 25, and conduit 27, with chamberintermediate the'passage,

Extending upwardly from the top of the inverted cup 24 is a tubularguide 29 slidably receiving therein'a holzlow actuating stem 30 of apumping element, which stem is connected directlywith the pump diaphragm23 t by washers 31 and 32 secured in place at the lower end of the stemby rivet or pin 33. Stem 30 is provided with a groove orneck portion 35,which receives a horse- A coil compression spring 37 is confined betweenthe washer 36 and the top of the cup 24, surrounding the tubular guide29 in such a manner as to tend to -urge'stem 30 and its connecteddiaphragm 23 upwardly. 1

Below the diaphragm is a chamber'or cavity 22 having a port38 inthe wallthereof connected by a passage 38a to the mixture conduit 11 posteriorof the throttle, so that, when the engine is operating, depress1onposterior to the throttle communicated to the cavity 22 forces the stem30 downwardlyto its extreme lower limit. against 'the compressive forceimposed by.the

' spring37.

i Also located within the constant level fuel chamber 16 is a verticalguide of rectangular cross-section (not shown) fortreceiving agooseneck' link 41 provided with an oifset portion 42 formed with ahorizontal ledge 43. Ledge 43 has'an aperture in its outer end portionslidably receiving the stem 30.' The upper, end portion of the stem 30is of less diameter than the lower portion, forming a shoulder 44, thefunction of which will be later described. An angular bracket 45 has an.aperture at one end for slidably receiving the narrow portion of thestem 30, and has a pin 46-at its other end attached to the steppedmetering pin 18. This bracket 45 seats on the upper side of the ledge43, or on stem shoulder 44, whichever-happens to be .up-

--:pe1n 1ost, and itself providesa seatlfor asecond coil-.com-

pression spring 49 retained on the stem 30 by a keyed or otherwisesecured washer 50. Link '41, 42- is provided at its lower end with aconnection 51 in the form of a small link to an arm 52 rigid with thethrottle shaft 12, so. that,

upon movement of the throttle valve '13 in an opening direction, link41, 42 moves upwardly, carrying with it bracket 45, and therebyresiliently urging the stem 30 in an upwardly direction through thecompression spring 49. Upward movement of 'the stem 30 can produce acorresponding movement of :the diaphragm 23, which, in turn, will forcethe fuel trapped in the pumping chamber 25 through the outlet passage 27to the mixing conduit 11.

Likewise, when a decrease in suction occurs at'a greater rate than therate of opening of the throttle valve 13, compression spring 37 expandsand shoulder 44 on stem 30 engages bracket 45 to lift it from ledge 43to elevate the metering pin 18 independently of throttle movement. Whensuction remains high, even though the throttle is being opened,diaphragm '23 may prevent any appreciable movement of the stem 30. Underhigh suction conditions posterior to the throttle, upward movement ofthe link 41, 42, due to opening movement of the throttle, raises ledge43 and annular bracket 45 against the compression in spring 49, whilestem 30 remains nearly stationary. This upward movement of bracket 45 bythe throttle is relied on for raising the stepped metering pin 18, andthereby providing an increase in the rate of fuel supply to the nozzles.

During closing movement of the throttle, spring 49 again urges bracket45 downwardly against shoulder 44 or ledge 43, whichever is uppermost,so that the lowering of the metering pin is limited by one of theseelements.

From the detailed description as set forth above, the operation of theaccelerator pump may be described as follows: In the first place, themovement of the stem 30 in an upward direction, and actuation of thepump 23, is under the control of mechanical means hooked to the throttleacting against spring 49 to raise stem 30. This action is aided by aspring 37 and opposed in whole or in part by pressures posterior to thethrottle which are normally sub-atmospheric, acting beneath thediaphragm 23.

In the second place, actuation of the pump 23 is also under control ofsuction in cavity 22, since a drop in suction will cause actuation ofthe pump by spring 37 independent of throttle movement.

Action of the metering pin within its orifice is under the control ofmechanical means to be positively raised by opening of the throttle andto be positioned independent of the throttle by upward movement of thestem 30 independent of throttle action. metering pin is efiected by dropin the degree of suction posterior to the throttle acting on thediaphragm 23 and expansion of spring 37. It follows that the meteringpin may increase the flow of fuel to the mixing tube in response to (1)opening movement of the throttle, and (2) upward movement of the stem 30under action of the spring 37 in response to decreases in suctionposterior to the throttle.

The operation of the diaphragm type of accelerator pump, as a pump andas a means to position the metering pin, is entirely satisfactory solong as bubbles of air or gas do not become trapped in the inverted cup24 above the diaphragm 23. This cannot be avoided under certainconditions, such as during idling of the engine or after the engine hasben standing inactive. It will be readily recognized that, when thishappens, the bubbles may collect to form quite a large gas areaextending outwardly from the top of the dome-shaped cup to the orifice26, which vents to the fuel bowl of the carburetor. The effect of suchan accumulation produces an undesirable, nonuniform response in thedelivery of fuel from the outlet conduit 27 during the pumping action ofthe diaphragm 23, and irregular response of the pump in positioning the-metering pin, since there isno uniform damping of pump action .due tofuel in the pumping chamber. To avoid the This later movement of thetion, a means is provided to bleed otf gases from this pocket to thesurface of the fuel in the fuel bowl. When gas is eliminated, pumpresponse is regular in its action for uniform damping of metering pinmovement.

Turning now to Fig. 1, a structure to carry out this purpose will bedescribed. The stem 30 of the diaphragm pump is made tubular, as shownin 60, and is closed at both ends. Immediately adjacent the upper wallof the inverted cup 24, a port is provided, indicated as 61, open to theinterior of the pumping chamber when the stem 30 is in its lowermostrange of positions and closed in its upper range. This port may be ofany desired size or shape. Generally, such a port is constructed by adrilling operation, and for that reason is shown to be round. However,the port 61 may be of irregular shape, if desired, so that upward stemmovement will result in a pronounced effect on pump delivery due toprogressive closing of the port as it enters the guide 29. Thus the ventcan be designed to perform ametering function for varying pump dischargeduring portions of its stroke, since it will be understood that part ofthe pump discharge can be bypassed back to the fuel bowl through thevent passages. The opposite end of the stem beneath the necked portion35 is provided with similar ports 62 connecting the hollow interior ofthe stem with the fuel bowl.

In such a structure as that above described, any gases which may becometrapped within the upper portion of the inverted cup 24 will escape fromthe pumping chamber by way of the port 61, tubular stem 60, and port 62,above the upper surface of the fuel in the fuel bowl, from which spacethey may be vented, in turn, to atmosphere or mixing tube 11 by anysuitable well known structure for this purpose. This modification of thepump stem provides a vent when the pump diaphragm is in its lower rangeof positions, which vent is automatically throttled on upward movementof the stem 30 as the port 61 enters the tubular guide 29. Thus the portand guide act together like a valve. Obviously, the liquid displacementof the pump is not affected adversely if the port 61 is small, becauseany fluid flowing through this vent passage is metered, by the port 61,which closes during the initial portion of the effective pumping stroke.

Turning now to the modification shown in Figs. 3 and 4, Fig. 3 shows thepump stem in its lowermost position, and Fig. 4 shows the pump stemraised to approximately intermediate position. The structure is similarto that above described, and like parts are accordingly indicated bycorresponding reference characters. This pump is provided with aninverted cup 24 having a downwardlyfacing fuel intake port indicated as63, in which is mounted a valve seat element 64 containing a verticallyarranged passage 65. Valve seat element 64 is mounted in the cup bycooperating screw threads 66 on the element and on the cup. This elementis also provided with a valve seat 67, upon which is mounted a valvedisk 68 retained adjacent the seat by a spring ring device 69 seated ina groove in a vertically arranged valve chamber 71. Passage 72 connectswith the valve chamber, and leads downwardly to a port open to the pumpchamber.

As explained in the previous embodiment shown in Fig. 1, the pump stemin Figs. 3 and 4 also has a gas vent. In this modification, stem 30 isprovided with a similar tubular central passage 75 closed at oppositeends except for a plurality of vertically spaced ports 76 opening intothe pump chamber, and a plurality of radially spaced combined gas outletand/or liquid metering ports 77 opening to the fuel fowl. The functionof ports 77 is not only to vent the pump, but also to meter the amountof fuel to escape by way of the tubular stem 75 during the actualpumping stroke. In this respect, Fig. 3 differs from Fig. 1, wherein themetering is performed by ports .61.

It will :be understood that the operation of the pump shown in Figs. 3and 4 is controlled in the same manne as illustrated in Fig. '1andexplaiiied aha; f the vent'and pump intake,however,diifer slightlyinoperation. It will .be noted that the intakelfor the pump is adownwardlyfacmg passage whereby induction into the pump of vapors.cation,'pump inlet 26 is intended to act merely as an auxiliarypassalgeto allow the fuelto leak in and fill the pump chamber when the engine isnot operating, and thereby replace fuel evaporated from the chamber andescapingin the form of vapors through the vent.

The structure for venting the pump, and thereby eliminating anyaccumulation of gases and vapors collecting in. the inverted cupadjacent thestem, is accomplished in a slightlyditferent manner. In thisinstance, a plurality of vertically spaced ports 76, all of which areopen in the lower range of positions of the stem 30, and which areprogressively throttled during the upward stroke of the pump, performthe venting action. From an inspection of Fig. 3 it will be obvious thatany accumulation of gases adjacent the stem, as shown by dotted line inthis fig., may'escape by way of the topmost one of the ports 76, tubularstem 75, and radially spaced ports 77. When the pump is in its lowermostrange of positions, the upper one of ports 76 is positioned toaccommodate this function. As the stern rises during its operativepumping stroke, ports 76 are successively sealed off or throttled, asshown in Fig. 4, and each of the ports is successively raised to aposition wherein it becomes effective as a vent, so that, as the pumpapproaches or reaches intermediate range, only one of the ports 76, thelowest, remains open, but it is in turn positioned so as to beelf-ective as a vent. Above this range a vent is not necessary, and allthe ports are throttled. In this respect the ports 76 act as valves.

Since it is possible for liquids, as well as gases, to escape throughthese ports, the size of the ports must necessarily be restricted, orthe pump will have very little displacement, even though ports 77 areabove the outlet from fuel nozzle 27a and during pump action fuel wouldnormally reach nozzle 27a before leaking out by way of ports 77. Thisrestriction to the liquid escape is performed generally by metered ports77. However, this function of ports 77 may be materially affected bysuccessive closing of ports 76, if desired. In the initial portion ofthe pump stroke, the diaphragm movement tends to be rapid and, for thisreason, the venting area provided by the ports 76 may be considerablylarger without affecting the capacity of the pump materially. Before thestem reaches its intermediate range of positions, however, the pumpingaction is slowed to some extent because the pumping pressure exerted bythe spring 37 has decreased. For this reason, the venting area should becut down, and the possible route of escape of fuel through the ventshould be materially decreased. The structure shown in Figs. 3

and 4 quite clearly illustrates all of these desirable features and, atthe same time, maintains a gas vent open until throttle-opening positionor manifold pressure has positioned the pump in the intermediate rangeor portion of its stroke.

It has been found that the venting means described materially benefitsthe action of the carburetor and combines with the specific actuatingmeans for the pump to effect a substantial improvement in theperformance 'of the carburetor as a whole.

Only two embodiments of the present invention have been illustrated, butit will be obvious to those skilled in the art that numerous othermechanical devices of well known form and type might be combined to. beoperated by the pump-actuating mechanism herein disclosed to performexactly the same function and achieve the same results. It is believed,therefore, that the claims appended as stand teata 'mttr t; the light ofthe atest disclosure, but not restricted thereby.

1. In a carburetor, the combination'ofa throttle-controlled fuel and airmixing tubeg alconstant level fuel chamber and passage to said tube, apump including a pumpingchamber intermediate said passage, a guide inone of said chambers and a pump element having a stem in said guideextending above the fuel level in said other chamber, means responsiveto throttle action for operating said pump and means forventing one ofsaid chambers comprising a passage in said stem with openings above thefuel level in the other chamber, a metering means for said passage, anda pump-controlled means for progressively throttling said vent means.

' 2. ha carburetor, the combination of a throttle-controlled fuel andair mixing tube, a constant level fuel chamber and passage to said tube,a pumpincluding. a pumping chamber intermediate said passage, a guide inone of sald chambers and a pump element having a stern in said guideextending above the fuel level in the other said chamber, meansresponsive to throttle action for operating said pump and means forventing one of said chambers comprising a passage in said stemcommunicating with the other said chamber, a metered opening above thefuel level in said fuel chamber, and a pump-controlled means forprogressively throttling said vent means.

3. In a carburetor, a throttle, a source of fuel, an accelerating pumpincluding a pump chamber and a guide in said source, a pumping elementin said chamber, a stem on said element slidable in said guide,resilient means under control of said throttle for operating said pump,and a vent for said pump comprising a passage within said guidecommunicating between said chamber and said source, open in one range ofpositions of said pumping element and closed within another range ofpositions thereof in response to change in throttle position.

4. In a carburetor having a throttle, the combination of a source offuel, an adjustable fuel metering device, a resiliently operated meansfor adjusting said metering device under control of said throttle,including a damping mechanism having a chamber in communication withsaid source, a vent for gases and vapors in said mechanism leading fromsaid damping chamber to atmosphere, and means for throttling said ventfor producing uniform adjustment of said metering device in response toaction of said resilient means.

5. In an accelerating pump structure for a carburetor having a fuelchamber, a pump chamber separated from said fuel chamber, a fuel inletfrom said fuel chamber to said pump chamber, a fuel outlet from saidpump chamber, a gas vent in a wall of said pump chamber, a pumpingmember movable in one direction in said pump chamber to draw fuel fromsaid fuel chamber through said fuel inlet into said pump chamber andmovable in another direction to discharge fuel from the pump chamberthrough said outlet, and an element movable with said pumping member forclosing said gas vent upon initial movement of said pumping member insaid other direction from its charged position.

6. In an accelerating pump structure for a carburetor having a constantlevel fuel chamber, a pump chamber separated from said constant levelchamber by a wall hav ing a stem guide bearing aperture, a fuel inletpassage leading from said fuel chamber to said pump chamber, a movablepumping element in said pump chamber, a stem secured to said pumpingelement and extending upwardly through said bearing aperture, a gas ventpassageway in said stem having an inlet port disposed within the pumpchamber below and adjacent said wall when said pumping element is in alower retracted position, said gas vent passageway having an outlet portdisposed to vent gases to the atmosphere, a fuel outlet passage leadingfrom said pump chamber, and means to move said pumping element upwardlyfrom its retracted position toward 7 said wall to first close said inletport within said wall and then to force fuel from said pump chamberoutwardly through said fuel outlet.

7. In an accelerating pump structure for a carburetor having a constantlevel fuel chamber, a pump chamber disposed below said fuel'chamber andseparated therefrom by a wall having a stem guide bearing aperture, afuel inlet passage leading from said fuel chamber .to said pump chamber,a pump element in said pump chamber, a stem secured to said pump elementand extending upwardly through said bearing aperture into said fuelchamber, a gas vent passageway in said stem having an unobstructed inletport disposed within the pump chamber below and adjacent said wall whensaid pump element is in a lower retracted position, said gas ventpassageway having an outlet port disposed to vent gases into said fuelchamber above the fuel level therein, a fuel outlet passage. leadingfrom said pump chamber, resilient means to move said pump elementupwardly from its retracted position toward said Wall to first confineand close said inlet port within said wall and then to force fuel fromsaid pump chamber outwardly through said fuel outlet, and means formoving saidv pump element toward its retracted position to draw fuelfrom said'fuel chamber intosaid pump chamber.

References Cited in the file of this patent UNITED STATES PATENTS2,003,420 Babitch et a1 June 4, 1935 2,022,660 Flint Dec. 3, 19352,080,391 Rockwell May 11, 1937 2,130,915 Whisler Sept. 20, 19382,212,946 Mock et al Aug. 27, 1940 2,235,797 Carlson Mar. 18, 19412,299,863 Trisler Oct. 27, 1942 2,619,333 Carrey Nov. 25, 1952 FOREIGNPATENTS 422,850 Great Britain Jan. 17, 1935

